The present invention relates to an image-forming apparatus for developing an electrostatic latent image or a magnetic latent image in the electrophotographic method and the electrostatic printing method, particularly, to an image-forming apparatus comprising a rotary developing device in which a plurality of developing units arranged around the axis are rotated so as to bring the desired developing unit to a developing position.
In the rotary developing device, toner is scattered from the open portion of the rotating developing unit so as to be accumulated in, for example, the region in which the developing device, the photosensitive body and the intermediate transfer member are positioned adjacent to each other. A large amount of the toner thus accumulated is dropped so as to give rise to the problem that an undesired portion within the image-forming apparatus is contaminated with the dropping toner, thereby forming a defective toner image. To avoid the difficulty, a toner receptacle is arranged so as to recover the scattered toner, as disclosed in, for example, Japanese Patent Disclosure (Kokai) No. 11-305543.
However, the toner is frictionally charged within each developing unit, with the result that the surface of the casing covering the rotary developing device tends to be charged and, thus, the toner that was scattered and accumulated within the casing tends to be attached to the surface of the casing. If the developing device is rotated under this state, vibration of the developing device causes the attached toner to drop from the casing surface so as to further scatter the toner, thereby contaminating the image-forming regions such as the image carrier and the intermediate transfer member.
It was customary in the past to arrange a recovery roller at the positions where the toner tends to be scattered so as to recover the scattered toner or to arrange a sucking device for recovering the scattered toner. However, these recovery methods cause the image-forming apparatus to be come complex in construction, and to be made bulky. In addition, the manufacturing cost of the image-forming apparatus is increased.